Tet (テト, Teto) is the One True God and resides in a king chess piece. He assumed the title after the eternal war, which he won despite not participating in the war at all. After both Shiro and Sora defeated him in a game of Internet chess, he summoned the siblings to Disboard.
To challenge Tet for the title of the One True God, one must collect all pieces of different chess from 16 races. This means that, under the tenth rule of the Ten Covenants, one must defeat or unite all 16 races before being able to play against him.
